DAF LF45, LF55 Series. Manual - part 288

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 200416

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General

BE ENGINE FUEL SYSTEM

ΛΦ45/55 series

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2.2 SYSTEM DESCRIPTION, ECS-DC3 FUEL SYSTEM

The fuel lift pump (4a) draws the fuel from the fuel 

tank (1) through the cooling plate (2) of the 

electronic unit (3).

The purpose of the cooling plate (3) is to ensure 

that the electronic unit does not become too hot.

The fuel lift pump (4a) is fitted against the high-

pressure pump (4c) and is driven by the camshaft 

gear.

From the fuel lift pump, fuel is forced towards the 

fuel fine filter (5).

After the filter, the fuel enters the high-pressure 

pump (4c) via the fuel pump control solenoid 

valve (4b), which controls the amount of fuel 

going to the high-pressure pump. Fuel not taken 

in by the high-pressure pump returns via the by-

pass valve (4d) to the fuel lift pump supply pipe 

and part of it is used for lubricating the high-

pressure pump.

The high-pressure pump forces the fuel under 

high pressure to the fuel rail (6). The fuel rail 

distributes the fuel among the injectors (7). The 

fuel rail (6) also functions as an accumulator to 

ensure that large fluctuations in pressure, 

resulting from injector openings and pump 

pressure pulses, are prevented as much as 

possible.

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 200416

General

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ΛΦ45/55 series

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The pressure in the fuel rail is registered by the 

rail pressure sensor (6a). The electronic unit uses 

this data to control the high-pressure pump (via 

the fuel pump control solenoid valve), so that the 

rail pressure can be kept at the desired level. The 

desired pressure is not constant, but depends on 

the operating conditions.

A pressure relief valve (6b) is fitted at the end of 

the fuel rail. If the pressure in the fuel rail rises too 

high (in emergencies only), this valve ensures 

that the excess fuel flows back to the return pipe. 

The return pipe is connected with the return pipe 

to the fuel tank (1).

The electronic unit uses the present rail pressure 

to calculate the time during which the injector 

needs to be opened in order to obtain the desired 

injection quantity.

A pressure relief valve (8) connects the injector 

leak-off ducts in the cylinder head with the return 

pipe to the fuel tank (1). This pressure relief valve 

prevents the fuel from flowing out of the injectors 

when the engine has stopped running.

If the system has been "open", the fuel system 

can be bled using the primer pump (2a), which is 

integrated in the water separator/coarse filter 

(2b).

The return pipe to the tank contains a check valve 

(9), which is normally closed. As soon as the 

quick release coupling on the fine filter head is 

disconnected, the return pipe closes so that it 

cannot empty.

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 200416

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General

BE ENGINE FUEL SYSTEM

ΛΦ45/55 series

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2.3 OVERVIEW DRAWING, FUEL PUMP

1.

Attachment bolt

2.

Fuel pump control solenoid valve

3.

O-ring

4.

O-ring

5.

Fuel pipe connection

6.

Copper ring

7.

Lift pump

8.

High-pressure pump

9.

Circulation valve

10. O-ring

11. Copper ring

12. Fuel pipe connection

13. High-pressure pipe connection

14. Spring

15. Ball

16. Oil seal

17. O-ring

18. Adapter ring

19. O-ring

20. Gear wheel 

21. Sealing ring

22. Nut

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General

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ΛΦ45/55 series

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2.4 OVERVIEW DRAWING, FUEL RAIL

Overview drawing, fuel rail, < production date 
2003-49 (chassis number < 0L253643) 
The figure shows the connections to the injector 

pipes. The numbers indicate the cylinder number 

of the connection.

Overview drawing, fuel rail, production date 

 2003-49 (chassis number  0L253643) 
The figure shows the connections to the injector 

pipes. The numbers indicate the cylinder number 

of the connection.

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i400764

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i400873